[Morphological studies on preputial gland of mice--1. Light and transmission electron microscopic observations of preputial gland in male mice].

Male BALB/c mice isolated after weaning were housed two mice per cage at the age of 10 weeks. After 1 week, each pair of mice was observed for social dominance, and compared with control mice kept in isolation. The preputial gland in the socially dominant animal was histologically examined. The preputial gland consisted of a congregation of branched simple tubuloacinar gland and typical holocrine secretion on morphological examination. Acinar cells in the dominant animals were large, multiplicative and hypertrophic compared with those of controls and subordinates. Dominant animals required copious secretion for attainment and maintenance of a dominant social position. Acinar cells of subordinates were very small, flattened and atrophied because fatty secretion particles filled the luminal duct. These accumulated secretion particles pressed the acinar cells and caused degeneration. Not only luminal acinar cells but also central acinar cells and some basal acinar cells were degenerated. Electron micrographs showed that basal acinar cells in dominant animals contained many mitochondria, agranular endoplasmic reticulum and free ribosomes in the cytoplasm, whereas those of subordinates contained myelin bodies and lipid droplets. Therefore, it is suggested that the synthesis of secretion particles in acinar cells of subordinates hardly occurred.